The present invention relates generally to network switching. More particularly the present invention relates to connection establishment over data links.
Multiservice network switches such as the BPX(trademark)8650 sold by Cisco Systems, Inc. of San Jose, Calif., may be used to provide a data path, or interface, between multiple sub-networks. Multiple sub-networks may operate according to different data link standard protocols. Examples of data link standard protocols supported by multiservice switches include, but are not limited to frame relay, voice, circuit emulation, T1 channelized, T3 channelized, and Asynchronous Transfer Mode (ATM).
FIG. 1 is a block diagram illustrating a prior art network 100 of switches. Connection routing control processes on the switches communicate with each other and set up connections through the switches. Network 100 includes a number of switches 102-108 that are coupled therebetween by way of port cards 132-146 and trunks 148-154. Network 100 also includes customer premises equipment (CPE) units 160 and 162 coupled to switches 106 and 108 by way of links 156 and 158 and port cards 143 and 147, respectively. Switches 102108 include control cards 112-118. The control cards include connection routing processors 122-128, respectively. Each connection routing processor determines a route through a network. Connection routing processors 122-128 communicate therebetween by way of a connection routing protocol. The connection routing processors set up end-to-end connections, building connections out of virtual circuits on trunks 148-154 and cross-connects on switches 102-108. A command line interface is used to input a request for an end-to-end connection in one switch. Such end-to-end connection, for example, connects one virtual circuit on a port 147 connected to CPE 162 to another virtual circuit on a port 143 connected to the other CPE 160. In this way, end-to-end virtual connections allow different CPEs to communicate across the network of switches.
FIG. 2 shows a prior art switch 200 that may be a node of a network. Switch 200 generally comprises a data path 225 and a command bus 227 to which a controller 205, and port cards 210, 215, 220 may be coupled. Port cards 210, 215 connect switch 200 to other switches or nodes of the network. Port card 220 is coupled to CPE A. The port cards may be configured in a number of different ways to allow communication between trunks and CPE via data path 225.
Controller 205 generally performs control functions for a single switch 200 using command bus 227. Controller 205 includes a connection routing protocol 207, a switch resource management software 208, and a configuration database 206. The configuration database 206 includes information regarding the configuration and capabilities of the port cards. Controller 205 also provides a user interface 235 that allows a user access to and control of switch 200. The user interface 235 is also used to configure switch 200 and connection routing protocol 207. Switch resource management 208 establishes and de-establishes switch connections under the control of the connection routing protocol 207.
Controller 205 treats switch 200 as a single network node, addressing all communications destined for switch 200 to a network address of switch 200. Controller 205 receives and processes connection routing protocol messages and determines which local resources are affected by the protocol message. If the protocol message affects a resource not present on controller 205, controller 205 translates the configuration information originally contained in the protocol message to a format suitable for use by a target port card. Controller 205 then transfers the translated configuration information to the target port card via command bus 227. A port card is a card interfacing to a link that is coupled to another link or CPE or another communication device. The port card receives and processes the configuration information. The port cards indicate to controller 205, using command bus 227, completion of the configuration operations. A major disadvantage of this switch and controller arrangement is that the single controller is limited to supporting a single network connection routing protocol. This limits the control of all of the resources of the switch to the single configuration supported by the connection routing protocol.
Typically, virtual circuit connections are supported by links that inherently support virtual circuits, such as ATM, frame relay, and x.25 links. Connection routing systems, such as Cisco""s AutoRoute(trademark) and the ATM forum""s private network-to-network interface (PNNI), are used only on these types of links or a subset thereof. PNNI is a common standard for ATM and frame relay networks that inherently support virtual circuits. One disadvantage is that in the prior art, the combination of a connection routing system and a virtual circuit switch does not allow sending packets of data on every link type. For example, no existing switch allows the forwarding of packets on virtual circuits, set up by a PNNI controller, from ATM links that support virtual circuits to Ethernet links that do not inherently support virtual circuits.
A data switching system is described to allow arbitrary types of connections to be established over arbitrary link types that include link types that do not inherently support virtual circuits. The data switching system includes a label switching system to establish virtual circuit connections over any link types. The data switching system also includes a connection routing and signaling controller, coupled to the label switching system, to determine routes for connections over any link types.
Other features and advantages of the invention will be apparent from the accompanying drawings and from the detailed description that follows below.